Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.10.0.1
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Jul. 31, 2018
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Property, Plant and Equipment [Line Items]            
Other operating expenses $ 250,000 $ 250,000 $ 0 $ 250,000 $ 0  
Asset Impairment Charges     0 $ 0 0  
Maturity of highly liquid investments       90 days    
Insurance coverage amount       $ 250,000    
Past due rent charge term       5 days    
Allowance for uncollectible accounts   959,000   $ 959,000   $ 705,000
Provision for doubtful accounts   149,000 23,000 412,000 443,000  
Tenant recoveries realized from previous charge-offs   0 0 0 0  
Finite-lived intangible assets, accumulated amortization   47,480,000   47,480,000   41,830,000
Amortization of intangible assets   2,990,000 5,090,000 $ 11,390,000 12,500,000  
Property management fee, percent fee       3.00%    
Asset management fee, percent fee       2.00%    
Development Fee, Percent Fee       5.00%    
Minimum percentage of taxable income to be distributed to stockholders (as percent)       90.00%    
Advertising   $ 36,000 $ 52,000 $ 194,000 195,000  
Provision for federal income taxes       $ 49,000   $ 15,000
Term of disqualification to be taxed as a REIT due to loss of REIT status       5 years    
Common Stock, Par or Stated Value Per Share   $ 0.01   $ 0.01   $ 0.01
Increase in cash provided by operating activities       $ 18,540,000 18,820,000  
Reduction in cash from investing activities       $ 21,021,000 (25,000)  
Accounting Standards Update 2016-18 [Member]            
Property, Plant and Equipment [Line Items]            
Increase in cash provided by operating activities         306,000  
Reduction in cash from investing activities         $ 333,000  
Building and building improvements | Minimum            
Property, Plant and Equipment [Line Items]            
Property, Plant and Equipment, Useful Life       5 years    
Building and building improvements | Maximum            
Property, Plant and Equipment [Line Items]            
Property, Plant and Equipment, Useful Life       40 years    
Rent and other tenant receivables            
Property, Plant and Equipment [Line Items]            
Recoveries related to tenant receivables   $ 2,780,000   $ 2,780,000   $ 2,340,000
New Lease [Member]            
Property, Plant and Equipment [Line Items]            
Commission fee, percent fee       6.00%    
Renewed Lease [Member]            
Property, Plant and Equipment [Line Items]            
Commission fee, percent fee       3.00%